LEDs are being used in various applications because they consume less power than and are smaller than light sources such as fluorescent lamps or incandescent lamps. In particular, an array in which a plurality of LEDs are connected to one another is being used as the light sources of lamps that are mounted on front sides, rear sides, and lateral sides of recent automobiles.
As the intensity of light emitted by LEDs increases, the magnitude of a current that passes through each LED increases. However, due to the characteristics of components of LEDs or the influences of LED manufacturing processes, the relationship between the intensity of light emitted by an LED and the magnitude of a current that passes through the LED may be different for different LEDs. In other words, even when the same magnitude of current passes through LEDs produced via the same manufacturing process, the LEDs may output light beams with different intensities. Since applications that use LEDs as a light source need light with a constant intensity, the intensities of light beams emitted by the LEDs need to be compensated for their deviations from the constant intensity.